[es6] support rest parameters in arrow functions (alternative)

test/cctest/test-parsing.cc

Index: test/cctest/test-parsing.cc
diff --git a/test/cctest/test-parsing.cc b/test/cctest/test-parsing.cc
index 12e1fe907ed558ad1564bf92f081521530e9ff84..4c966db3cdf99fa501c817481e390c7921d328dc 100644
--- a/test/cctest/test-parsing.cc
+++ b/test/cctest/test-parsing.cc
@@ -4828,6 +4828,8 @@ TEST(ParseRestParameters) {
                                     "function(){});"},
                                    {"(function(", "){ return args;})(1, [],"
                                     "/regexp/, 'str', function(){});"},
+                                   {"((", ") => args)(1, [], /regexp/, 'str',"
+                                    "function(){});"},
                                   {NULL, NULL}};
 
   const char* data[] = {
@@ -4844,7 +4846,8 @@ TEST(ParseRestParameters) {
     "...\t\n\t\t\n  args",
     "a, ...  \n  \n  args",
     NULL};
-  static const ParserFlag always_flags[] = {kAllowHarmonyRestParameters};
+  static const ParserFlag always_flags[] =
+      {kAllowHarmonyRestParameters, kAllowHarmonyArrowFunctions};
   RunParserSyncTest(context_data, data, kSuccess, NULL, 0, always_flags,
                     arraysize(always_flags));
 }